code: def __iter__(self):
      count = 0
      self.loaditer = iter(self.loader)
      self.preload()
      while self.next_input is not None:
          ch.cuda.current_stream().wait_stream(self.stream)
          input = self.next_input
          target = self.next_target
          self.preload()
          count += 1
          yield input, target
          if type(self.stop_after) is int and (count > self.stop_after):
              break
  
imports: import torch
  import shutil
  import dill
  import os
  from subprocess import Popen, PIPE
  import pandas
  from PIL import Image
  from .None import constants
label_desc: Use image node_id 4 for calling the DataPrefetcher obj's underlying member method code with example usage: obj.__iter__() without return types